Accelerating pump



July 11, 1961 N. ROMEO ETAL 2,991,984

' ACCELERATING PUMP Filed Aug. 25, 1958 4 Sheets-Sheet 1 INVENTORS WOJQQILM,A

July 11, 1961 N. ROMEO ET AL 2,991,984

ACCELERATING PUMP Filed Aug. 25, 1958 4 Sheets-Sheet 2 wlr w k QM Q,

A TTOEA E) July 11, 1961 N. ROMEO ET AL 2,991,984

ACCELERATING PUMP Filed Aug. 25, 1958 4 Sheets-Sheet 3 I I s I N VE NTORS A4574 20/1450 X; /FP/sMmc-K JMAPSl-i My; A

ATTORNEY July 11, 1961 N. ROMEO ETAL 2,991,984

ACCELERATING PUMP Filed Aug. 25, 1958 4 Sheets-Sheet 4 70741. All? FLOW 7/200617 CONDO/T 56 02 I26 INVENTORS W I /V/L 904450 54 Q/V/A/fidO J0 BY 210 3am valve/Wu FPEDEP/CKJMAPSH:

w it} W/ A TWP/YE) United States Patent 2,991,984 ACCELERATING PUMP Neil Romeo, St. Clair Shares, and Frederick J. Marsee,

Royal Oak, Mich., assignors to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Aug. 25, 1958, Ser. No. 756,862 Claims. (Cl. 261-34) This invention relates generally to pumps, and more specifically to accelerating pumps used in carburetors for internal combustion engines.

When an engine is called upon to accelerate rapidly, the air flow through the carburetor responds almost immediately to the increased throttle opening; however, the fuel, which is heavier than air, lags a substantial amount behind the increased air flow, thereby causing a leaning-out of the fuel-air ratio. The accelerating pump is designed to correct this condition by supplying liquid fuel until the other fuel metering systems once again are providing the proper mixture.

The performance of accelerating pumps, in general, has been seriously impaired by the fuel vapors trapped within the accelerating pump system. The presence of these vapors is attributed to those situations where an excessive amount of heat is created within the engine compartment, whether by a hot shutdown or prolonged idling of the engine. When vapor is trapped in the system, it displaces the volume therein which liquid fuel would normally occupy and therefore, When the accelerating pump is called upon for additional fuel, none will be supplied because of the absence of liquid fuel.

Accordingly, it is an object of this invention to provide means for removing any vapor within the accelerating pump system.

More specifically, it is an object of this invention to provide thermostatically controlled means for removing vapor from within the accelerating pump system.

Other objects and advantages will become apparent when reference is made to the following specification and illustration wherein:

FIGURE 1 is a side elevational view, with portions thereof cut away and in cross-section, of a carburetor embodying the invention.

FIGURE 2 is a perspective view of the carburetor shown by FIGURE 1, with portions thereof cut away and in cross-section and having the fuel bowl removed, with the exception of the accelerating pump and associated linkage.

FIGURE 3 is an enlarged view of the accelerating pump nozzle in cross-section, taken on a plane substantially through the center of the carburetor body and pump nozzle.

FIGURE 4 is a top plan view of the pump nozzle shown by FIGURE 3.

FIGURE 5 is an enlarged cross-sectional view of a modification of the invention, taken on the plane of line 5--5 of FIGURE 6 and looking in the direction of the arrows.

FIGURE 6 is a fragmentary cross-sectional view, taken on the plane of line 6-6 of FIGURE 5 and looking in the direction of the arrows.

FIGURE 7 is a graphical representation of the performance of one of the modifications of the invention.

Referring now in greater detail to the drawings, FIG- URE 1 illustrates a carburetor 10 having a body 12 with an induction passage 14 extending therethrough. The carburetor is provided with the usual choke valve 16 controlling the entrance of the air intake 18 and throttle valve 20 controlling the flow of combustible mixture to the engine intake manifold 22.

A main fuel system is defined by metering restriction 24, conduits 26 and 28 and nozzle 30, which discharges ice as required within the induction passage 14. An idle system having a minimum idle and a transfer portion is schematically comprised of restriction 32, conduits 34 and 36 and ports 38 and slot 40, which discharge selectively below the throttle valve 20. A fuel bowl 42, delining a chamber 44 and having an inlet 46, is secured as by screws 48 to the body 12 in a manner to supply all of the fuel systems with a source of fuel. An accelerating pump 50 is attached to the bottom of the fuel bowl and is adapted to be actuated by levers 52 and 98.

FIGURE 2 illustrates the pump 50 as being comprised of a reinforced diapraghm 54 secured to the bottom of the fuel bowl by a member 56, thereby creating a chamber 58. The chamber 58 communicates with chamber 44 of the fuel bowl 42 by means of a passage 59 having a gravity actuated ball check valve 60. Chamber 58 also communicates with the pump nozzle assembly 62 by means of conduits 64, 66, 68 and 70.

A screw 72 and housing 74 cooperatively defining a chamber 76 constitute the basic nozzle assembly. Nozzles 78, which may either be formed as part of housing 74 or secured thereto, communicate with chamber 76 and are directed towards the induction passage 14. The screw 72 is threadably received by the body 12 and a passage 80 formed in screw 72, is provided as a means of communication between chamber 76 and conduit 70. A seat 82 is provided within conduit 70, and a ball 84 and weight 86 are placed between the seat and chamber 76.

A separate conduit 88 formed in body 12 and housing 74 communicates between the atmosphere and chamber 90, which is substantially formed by body 12 and an insert 92. A calibrated passage 94 communicates between chamber 76 and conduit 88, while a second conduit 96, having a restriction 102, communicates at times between chamber and a source of engine vacuum.

A thermostatically controlled valve 104, suitably secured to insert 92, controls the amount of flow from chamber 90 to conduit 96. As the temperature increases, the flow is correspondingly increased. The valve 104 is comprised of a metering portion 106 connected at one end to a bimetallic element 108 which is in turn secured as by rivet 110 to insert 92 at its other end.

FIGURES 5 and 6 are modifications of the invention. All elements which are like or similar to those of FIG- URES 3 and 4 are identified with like reference numerals. It will be noticed that nozzles 112 differ from nozzles 78 in that a small restriction 114 is formed in the bottom portion. The housing 116 also differs in that separate conduits 118 and 120 pass about nozzles 112 and restrictions 114 and communicate between the atmosphere and branch conduits 122 and 124 of conduit 126, the latter being in comm-Lmication with chamber 90.

Operation The general operation of the accelerating pump is briefly as follows: When the throttle 20 is opened, the pump linkages 52 and 98 force the pump diaphragm 54 upwards. As the diaphragm moves up, the pressure forces the pump inlet ball check valve 60' closed, thereby preventing fuel from flowing back into the chamber 44. The fuel within chamber 58 then flows through conduits 64, 66, 68 and to conduit 70 where it causes the ball 84 and weight 86 to raise, thereby discharging the fuel from chamber 76 through nozzle 78 into the induction passage 14.

As the throttle is moved toward the closed position, the linkages 52 and 98 return to their normal positions and the diaphragm 54 is forced downwardly by spring 100. As the diaphragm returns to its original position, the pump inlet ball check valve 60 is opened and the chamber 58 is filled with fuel from the fuel bowl.

The specific improvement contemplated by the invention will be more readily appreciated if it is first assumed that the engine has been started after a period of hot shut-down. At this time, bimetal 108 will have moved the metering portion 106 some distance away from conduit 96, thereby allowing engine vacuum into conduit 88 and causing air flow therethrough. As the air passes by calibrated passage 94, the vapors existing within the accelerating pump system are drawn off into conduit 88 and subsequently into the engine intake manifold.

The degree to which portion 106 opens is of course related to and dependent on the temperature of the engine and the carburetor structure.

The operation of the modification illustrated in FIG- URES 5 and 6 is generally the same as that of the preferred embodiment. When the engine is started, air is drawn through conduits 118 and 120, thereby causing a decrease of pressure at the trailing surfaces of nozzles 112. The vapors are [then drawn through nozzle 112 and restrictions 114 into conduits 122 and 124 and subsequently to the engine intake manifold by way of conduit 126.

It should be noted that the restrictions 114 and 94 could be so determined so as to have a critical flow point. If this was done then it would be possible to have the air flow through conduit 88 or 126 increase steadily as temperature increased and yet have a maximum flow through restrictions 94 or 114, regardless of the flow through conduit 88 or 126. FIGURE 7 illustrates this possibility graphically.

- tion system, and temperature responsive means for increasing the rate at which said vapors are removed in accordance with temperature.

2. In a carburetor for an internal combustion engine having an idle fuel system, a main fuel system and an ac celeration fuel system, means operative upon engine operation for removing vapors from within said acceleration system, and means responsive to engine temperature means for increasing the rate at which said vapors are removed in accordance with engine temperature.

3. In a carburetor for an internal combustion engine having an acceleration fuel system, means operative during engine operation for removing vapors from within said acceleration system, said means comprising a conduit pneumatically connected to a source of engine vacuum and said acceleration fuel system, means disposed within said conduit at a point between said source of vacuum and said acceleration system for controlling the flow of vapor therethrough in accordance with engine temperature, said last mentioned means allowing a greater flow rate at higher temperatures than at low temperatures.

4. In a carburetor for an internal combustion engine having a body portion with an induction passage extending therethrough, a throttle valve controlling the flow of combustible mixture from said induction passage, an acceleration fuel system, a housing secured to said body portion and having a nozzle associated therewith adapted to discharge liquid fuel into said induction passage as required, conduit means communicating between a source of engine vacuum and air above said throttle valve, temperature responsive means for reducing the flow through said conduit means astemperature decreases, and a passageway formed between said housing and said body portion communicating between said conduit means and said acceleration fuel system.

5. In a carburetor for an internal combustion engine having a body portion with an induction passage extending therethrough, a throttle valve controlling the flow of combustible mixture from said induction passage, an acceleration fuel system, a housing secured to said body References Cited in the file of this patent UNITED STATES PATENTS 2,493,804 Carlson Jan. 10, 1950 2,625,382 Boyce Jan. 13, 1953 2,785,880 Olson Mar. 19, 1957 

